• 상하수도학회지
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• 제18권1호
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• pp.73-80
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• 2004

This study investigated the phenomena of membrane fouling by NOM and the effect of the fouling on removal of micro-pollutants. NOM has a great effect on decline of permeate flux. Permeate flow rate was reduced by 88% in RO and 34.8% in NF for 323hr operation period. Removal rate of $UV_{254}$, is 87.4% in RO and 78.5% in NF and removal rate of DOC is 42.7% in RO and 32.9% in NF for 2mg/l humic acid. Removal efficiency of the micro-pollutants by the RO and NF membranes fouled by humic acid was mostly lower than that by the new membrane. The concentration polarization which affects the flux and the rejection was thought to occur in the active layer of the membrane, as the membrane was getting fouled.

• Membrane and Water Treatment
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• 제6권4호
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• pp.323-337
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• 2015

Membrane Fouling was considered as major drawback in various industrial applications. Thus, this paper reviews the surface modification of polyethersulfone (PES) membranes for antifouling performance. Various modification techniques clearly indicate that hydrophilicity has to improve on the PES membrane surface. Moreover, the mechanism of fouling reduction with corresponds to various modification methods is widely discussed. Incorporation of hydrophilic functional groups on PES membrane surface enhances the surface free energy thereby which reduces the fouling. Characterization techniques adopted for the surface modified membranes was also discussed. These studies might be useful for the other researchers to utilize the modification technique for the applications of waste water treatment, chemical process industry and food industry.

• 멤브레인
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• 제21권2호
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• pp.171-176
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• 2011

분리막을 이용한 수처리 공정에서 유입 수에 함유된 부유물질이나 기타 오염물질이 막 표면 또는 내부에 축적 흡착 등의 막 오염현상으로 인해 막 성능 감소와 함께 막 분리 공정에 큰 영향을 미치게 된다. 본 연구에서는 막 표면에서의 막 오염현상을 실시간으로 모니터링 할 수 있는 기술을 연구하였다. 투명한 오염물질에 의한 분리막 표면 오염을 측정하기 위해 막 표면에 360 nm 파장의 가시광선을 조사하여 이미지를 R. G. B 값으로 추출하여 막의 오염현상을 실시간으로 모니터링 하였다. 추출된 이미지 중 400~499 nm 파장영역인 B 값이 가장 강도가 강하게 나타났다. 막 오염정도의 변화를 이미지의 강도 차이로 관찰함으로써 실시간 분석이 가능함을 확인하였다.

• 상하수도학회지
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• 제32권2호
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• pp.77-87
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• 2018

In this study, the effects of operating conditions on the formation of reversible and irreversible fouling were investigated in the filtration using ceramic membrane for water treatment process. The effect of coagulation pretreatment on fouling formation was also evaluated by comparing the performance of membrane filtration both with and without addition of coagulant. A resistance-in-series-model was applied for the analysis of membrane fouling. Total resistance (RT) and internal fouling resistance (Rf) increased in the membrane filtration process without coagulation as membrane flux and feed water concentrations increased. Internal fouling resistance, which was not recovered by physical cleaning, was more than 70% of the total resistance at the range of the membrane flux more than $5m^3/m^2{\cdot}day$. In the combined process with coagulation, the cake layer resistance (Rc) increased to about 30-80% of total resistance. As the cake layer formed by coagulation floc was easily removed by physical cleaning, the recovery rate by physical cleaning was 54~90%. It was confirmed from the results that the combined process was more efficient to recover the filtration performance by physical cleaning due to higher formation ratio of reversible fouling, resulted in the mitigation of the frequency of chemical cleaning.

• 상하수도학회지
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• 제16권6호
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• pp.717-725
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• 2002

A bench-scale submerged-type membrane filtration system (SMFS) was constructed to study a feasibility of membrane filtration for solid-liquid separation in water and wastewater treatment processes. In the case of applying the SMFS to a biological wastewater treatment process, so-called membrane bioreactor, aeration underneath membrane modules is usually employed in order to provide oxygen demand for microbial growth as well as to control membrane fouling. A study was investigated the effects of operation parameters by aeration intensity, feed concentration, foulant type and airlift pore size on critical flux. Critical flux tends to increase with aeration rate. Optimal aeration flow rate was found to be 10 L/min/module. Feed concentration and foulant type has a significant effect on membrane fouling and filtration performance. But downward position and pore size of airlift has no a significant effects on membrane fouling and filtration performance.

• 한국막학회:학술대회논문집
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• 한국막학회 2003년도 춘계 총회 및 학술발표회
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• pp.31-38
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• 2003

A pilot scale biofilter pretreatment-microfiltration system (BF-MF) was operated to investigate the effect of biofilter treatment in fouling reduction of microfiltration. Biofiltration was expected to reduce the membrane fouling by removal of turbidity and metal oxides. The hollow-fiber MF module with a nominal pore size of 0.1$\mu$m and a surface area of 8m$^2$ was submerged in a filtration tank and microfiltration was operated at a constant flux of 0.5 m/d. Biofiltration using polypropylene pellets was performed at a high filtration velocity of 320 m/d. Two experimental setups composed of MF and BF/MF, i.e., without and with biofilter pretreatment, were compared. Throughout the experimental period of 9 months, biofilter pretreatment was effective to reduce the membrane fouling, which was proved by the result of time variations of trans-membrane pressure and backwash conditions. The turbidity removal rate by biofiltration varied between 40% to 80% due to the periodic washing for biofilter contactor and raw water turbidity. In addition to turbidity, metals, especially Mn, Fe and Al were removed effectively with average removal rates of 89.2%, 67.8% and 64.9%, respectively. Further analysis of foulants on the used membranes revealed that turbidity and metal removal by biofiltration was the major effect of biofiltration pretreatment against microfiltration fouling.

• 멤브레인
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• 제27권5호
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• pp.434-440
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• 2017

본 연구에서는 역전기투석 공정에서 발생 가능한 막오염 현상을 in-situ로 측정하기 위하여 임피던스 스펙트로스코피 방법을 도입하여 실제 발생한 막오염 현상 측정 방법을 제시하였다. 얻어진 임피던스 데이터를 활용하여 Nyquist 도시법과 어드미턴스 도시법으로 스펙트럼을 도시하였으며 두 도시법 모두 유의미한 막오염 현상을 감지할 수 있었다. 또한 초기 막오염 현상에서 음이온 교환막 표면에 막오염물의 불안정한 축적 현상 및 역전기투석 공정의 운전 시간에 따른 막오염층의 구조적 변화를 감지할 수 있었다.

• 상하수도학회지
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• 제30권5호
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• pp.545-551
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• 2016

This study compares characteristic of membrane fouling in MBR-RO systems. In lab. scale MBRs test, MBRs were operated at different Flux(10, 20, 30 & 40 LMH) and temperature(10, 15, 20, 25 & $30^{\circ}C$). The results show that MBR permeate was measured lower amounts of organic substances in Higher flux and lower temperature and led to lower RO fouling rates. The main cause was that due to cake fouling formed on membrane surfaces in MBRs. Under both cases, Cake layer of membrane surfaces formed in MBRs removed RO fouling factors, polysaccharide and protein, because of cake layer attached on membrane surfaces greater amounts of organic substances. This study implies that optimization of MBR with operating conditions is a crucial strategy to RO membrane fouling control.

• Membrane and Water Treatment
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• 제3권4호
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• pp.221-230
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• 2012

This study employed the modified fouling index (MFI) to determine the performance of a two-step recycling system - a membrane filtration integrated laminar flow water storage (LFWS) tank followed by an ion exchange process to reclaim ultrapure water (UPW) from the wastewater generated from semiconductor wafer backgrinding and sawing processes. The first step consisted of the utilization of either ultrafiltration (UF) or nanofiltration (NF) membranes to remove solids in the wastewater where the second step consisted of an ion exchanger to further purify the filtrate. The system was able to produce high purity water in a continuous operating mode. However, higher recycling cost could be incurred due to membrane fouling. The feed wastewater used for this study contained high concentration of fine particles with low organic and ionic contents, hence membrane fouling was mainly attributed to particulate deposition and cake formation. Based on the MFI results, a LFWS tank that was equipped with a turbulence reducer with a pair of auto-valves was developed and found effective in minimizing fouling by discharging concentrated wastewater prior to any membrane filtration. By comparing flux behaviors of the improved system with the conventional system, the former maintained a high flux than the latter at the end of the experiment.

• 멤브레인
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• 제13권4호
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• pp.283-290
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• 2003

BSA 용액을 대상으로 한 dead-end 및 cross-flow 한외여과에서 막모듈에의 초음파 조사가 막성능 향상에 미치는 효과를 연구하였다. 이 결과 막모듈에의 간헐적 또는 연속적 초음파 조사는 막오염의 형성 억제 및 막오염 층의 제거에 상당한 효과가 있음이 확인되었다. 초음파 조사에 의한 막성능 향상 효과는 막오염을 크게 유발시키는 운전조건(도입액 농도와 TMP가 높고, 유량이 낮은 운전조건)일수록 더 컸으며, 막모듈에 초음파를 조사시키면 조사시키지 않은 경우와 비교할 때 dead-end 한외여과에서는 최대 약 1.9배, cross-flow 한외여과에서는 최대 약 1.5배의 투과플럭스 향상을 얻을 수 있었다.